star probe

[Ralph Barrier]

Could you give me any information on how to use the star probe that I have? We did not go over this at all in my cmm class. The star probe I have 4 legs, each with a 2mm ruby. From the center hub (which is around 5.5 mm dia.) to the center if ruby is around 15mm. Across from end to end is of course 30mm. I think I can build a tip using this and the parts in the box. I don’t know how to describe it. All I have in description of the tip is 2X18MMSTAR and also a 10BY6.5STAR. I’m assuming that I can use the 2x18 with 18 being distance from ruby center to back part of star hub (with the 4.5mm long connector thru star hub).?? All I found for each or the 4 “arms” were TIP2BY10MM which doesn’t look exact as far as the length goes.

How can I set this up, as far as making all the physical connections and descriptions? Also, how do I calibrate it? How do you know where to position the star so that it will come out along the X and Y axis when put on the machine?

Sorry for all these questions at one time. I know nothing on this.

Thanks.

[Wes Cisco]

The short answer is you should do a search of this forum for "calibrate star probe", you will find a couple of long threads. The tip lengths are from the *center* of the ruby to the seating shoulder of the shank. (not the tip of the ruby to the end of the thread). When building the probe you should find all the components in your probe files it should look something like: extension>star5way>tip1>tip2>tip3>tip4>tip5.

Calibration can be very rough. You need a dual artifact in many instances. At least one person has claimed they can calibrate on a single sphere artifact, but I could not get this to work for me. I have a great document that covers how to calibrate a star probe on a dual artifact that I downloaded from one of those threads I mentioned. I will email it to you if you send me a Private Message with your email address.

I do not have time to get more in depth just now. A search should help answer your remaining questions. I do Hope This Helps.

[Matthew D. Hoedeman]

Another thing, if it won't run in DCC mode due to length differences in the 'data build-up' to the 'actual' build up, do it all in manual mode. It will then have the correct lengths and locations for all the tips for all the angles you calibrated and it will run them correctly the next time around and every time after that. If the build-up difference is the problem as described, any new angles you add will also need to be done in manual mode the first time through, it will NOT use the calibrated values to 'guess' where any new ones are, they will still be to 'data'.

And yes, you will need a double artifact IF: (and this is just one example of why you will need one, there are many more)

1) Your head, at 0,0, points straight down
2) You need to calibrate the tip that points straight UP with the head at a 90,x angle
3) The shaft of your artifact runs straight up and down

Now, this is just one instance showing when you would need a double artifact OR just 2 different artifacts. The only thing that you MUST do when using 2 (or more) artifacts is that you MUST locate them BOTH using the same tip (and only 1 tip) for an initial calibration. This means, put the artifacts on the table. Select 1 tip (preferably T1A0B0, much prefered!) and then select the tool (artifact) and tell it to measure, but that the tool is in a new location. Once that is done, select that SAME tip, select the OTHER tool and tell it YES, that tool is alos in a new location. Then, you can DCC calibrate ALL the tips using which ever tool you need. At least, this is my understanding of how you use multiple tools for calibration. ALL the tools must be located using the same tip (apples to apple, eh?).

[Wes Cisco]

Ok, I have a bit of time this morning. Here is the document on double artifact calibration. This worked great for me, but due to the postition of my artifact and the configuration of my particular star probe I could not use tip 1 for the intial calibration on each artifact. I agree tip 1 is strongly preferred, but other tips will work as long as you calibrate both spheres with the same tip before calibrating all. HTH.